Various types of drainage systems are used to transport waste fluid from a source to a desired collection point. Gravity drainage systems, for example, use the pull of gravity to transport waste fluid. Such systems have many drawbacks. For example, options for the layout of gravity drainage piping are limited since the piping must be located below the waste fluid source and must continuously slope toward the collection point. The waste fluid source is often located on a concrete pad, so piping must be laid out before the concrete is poured. In addition, it is overly difficult to renovate or add plumbing fixtures to a gravity drainage system due to the piping location requirements. For example, handicapped-accessible toilets must be added to the washrooms in many buildings to meet the requirements of the Americans with Disabilities Act (ADA). Such renovation is performed on site, and may interrupt plumbing service for extended periods of time. In addition, personnel are often displaced during renovation, resulting in loss of production time. Furthermore, tenants of a building may be reluctant to carry out renovations to gravity drainage piping since any such improvement becomes an integral fixture of the building, and therefore must remain upon termination of the lease.
Vacuum drainage systems provide an alternative to conventional gravity drainage piping. Vacuum systems typically comprise a fixture, such as a toilet or a sink, connected to an existing fluid supply. The fixture has a drain for discharging waste fluid. The drain is connected by vacuum piping to a vacuum source which creates a negative pressure in the vacuum piping. A valve is disposed in the vacuum piping and is selectively operated to transport waste fluid from the drain to the vacuum piping and ultimately to a collection tank. As a result, the vacuum piping may be located above the waste fluid sources and may even run vertically upward, since vacuum, rather than gravity, is used to transport the waste fluid. This flexibility in locating the vacuum piping, therefore, simplifies and shortens the time needed to install and renovate plumbing fixtures. When installing or renovating a conventional vacuum drainage system, however, most of the plumbing fixtures and piping are assembled on site, and therefore many of the problems associated with gravity drainage systems are also present in vacuum drainage systems. For example, installation and renovation of conventional vacuum drainage systems still interrupts plumbing service and displaces personnel for overly lengthy periods of time.
In addition, such conventional vacuum drainage systems have typically been used in large-scale applications, such as in hotels, prisons, and shopping centers. Such systems typically comprise multiple large storage tanks and vacuum pumps, and extensive piping networks, with the major components of the system being housed in a mechanical room. In addition to housing components of the vacuum source, the mechanical room also serves to contain noise generated during operation of the vacuum drainage system. It is not feasible, however, to use such a vacuum drainage system to collect waste fluid from a few additional plumbing fixtures, as may be added in a typical office or other small-scale renovation. Furthermore, in certain spaces, such as an office building, a separate mechanical room is not typically available to house the components of the vacuum drainage system.
Conventional vacuum centrals have further been constructed on an open frame or in a free-standing arrangement in which the components are provided separately, without a frame. While an open frame facilitates access to interior components, the noise level generated by the system is undiminished and the system in general has an appearance which is unsuitable for certain applications, such as in an office.